Pivotally mounted disconnect switch contacts



June 16, 1964 L R, BARR 3,137,778

PIVOTALLY MOUNTED DISCONNECT SWITCH CONTACTS Filed April 16, 1962 UnitedStates4 Patent Office 3,137,778 Patented June 16, 1964 3,137,778PIVOTALLY MOUNTED DSCONNECT SWRTCH CONTACTS .lames R. Barr, Rome, Ga.,assigner to General Electric Company, a corporation of New York FiledApr. 16, 1962, Ser. No. 187,575 4- Claims. (Cl. 20G-164) This inventionrelates to an electrical switch and more particularly to improvements indisconnect switches for liquid filled transformers.

Heretofore, switches of this type have comprised a movable blade contactwhich is adapted to be engaged on opposite sides and pinched between apair of contact fingers of the other switch contact. In order to carrythe necessary current, these contact 'fingers have been electricallyconnected to the circuit through heavy metallic braid or the like whichis relatively stiffr and which interferes with the proper action of thecontact fingers' both as to the proper contact pressure during thepinching action and also as to proper alignment of the contacts in theirplane over relative motion.

In accordance with this invention, there is provided an improved switchin which the necessity for fiexible or semi-flexible connectors or leadsbetween the contact fingers and the rest of the circuit is dispensedwith and in place thereof a bail and socket type electromechanicalconnection is used. This ball and socket connection functions not onlyas a universal movement type of mechanical joint, but also because ofrelatively high mechanical pressures between the parts, it also providesgood electrical connection between the parts.

Another feature of the invention is the provision of novel means foradjusting the relative position of the two contacts in a directiontransverse to their plane of engagement for the purpose of aligning themfor proper engagement and disengagement.

An object of the invention is to provide a new and improved electricswitch.

Another object of the invention is to provide a new and improvednon-arcing duty disconnect switch for liquid filled transformers.

The invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

In the drawing, FIG. 1 is a side elevation view partly in section online 1 1 of FIG. 2, of a preferred embodiment of the invention, and FIG.2 is a plan view from the top thereof. j

Referring now to the drawing, there is shown therein a blade contact 1which may be made of any suitable material such as copper, and which isshown mounted for rotation about a pivotable support 2, in the plane ofFIG. 2 and, therefore, in a plane perpendicular to FIG.

l. For facilitating engagement and disengagement of the switch contacts,the blade contact 1 preferably has its leading and trailing edgeschamfered or beveled as indicated at 3. As indicated by the arrows 4 inFIG. 2 the blade contact 1 may be moved in either direction about itspivotable support 2.

The other contact of the switch is a more complex assembly designatedgenerally by reference character 5. It can either be fixedly mounted orpivotally mounted on a support 6 and rotated in either direction asindicated by the arrows 7 in FIG. 2 in the same plane as the bladecontact 1.

Ordinarily, of course, it will not be necessary for both of the contactsof the switch to be movable and one can be fixed. However, it isimmaterial to the invention in its broader aspects which one of thecontacts is a movable one and which is the fixed one, the only essentialfeature being that they be relatively movable in a generally commonplane parallel to the paper in FIG. 2 and perpendicular to the paper inFIG. 1.

The contact assembly 5 comprises a pair of duplicate contact fingers 8which may be made of any suitable material such as copper. They aremounted on a common central supporting member 9. The double contactfingers 8 preferably are curved at their outer ends as indicated at 10for facilitating engagement with the blade contact 1 which engagement isa wiping engagement while the switch is opening and closing.

The contact fingers 8 are supported from the central member 9 by thefollowing construction. There are two pairs of projections extendingfrom opposite sides of the central member 9, one pair of projectionsbeing identified as 11 and 11 and the other pair of projections beingidentified as 12 and 12. The pair of projections 11-11 are alignedtransverse to the plane of relative movement of the contacts andlikewise the pair of projections 12-12' are aligned transverse to theplane of relative movement of the contacts. However, the pair ofprojections 11-11 are removed from or farthest away from the bladecontact 1 and the pair of projections 12-12 are between the bladecontact and the pair of projections 11-11. The projections 11-11 havehemispherically shaped ends 13 and 13 from which extend outwardly,reduced diameter projections 14 and 14. The edges of circular holes 15and 15' in the contact fingers 8 and of a diameter slightly less thanthe diameter of the hemispherical sections 1,313 are seated on thosehemispherical sections so as to produce a ball and socket type jointpermitting universal pivoting motion of the contact fingers 8 about theends of the projections 11-11. Actually, if desired, the projections11-11 may be the ends of a unitary pin 16 passing through the supportingmember 9. As shown, they are fastened in any suitable manner to thesupporting member 9 such as by brazing as' indicated at 17. Theprojections 16S-14' serve as limit stops and facilitate mounting thecontact fingers S on the projections 11-11.

The projections 12,-12 are opposite ends of a common pin 18 passingthrough the member 9 and pin 18 is positioned by and free to slide insleeve 19. Seated in suitable openings in the Contact fingers 8 areeyelets 20 and Ztl' between the bottoms of which and washers 21 and 21secured by pins 22 and 22 are compression springs 23 and 23 for biasingthe ends 10 of the contact fingers 8 toward each other so that they willpinch the contact blade 1 when it is moved between them so as to makegood electrical contact.

For preventing the ends 10 of the contact fingers 8 from moving tooclose together so as to interfere with the proper entrance of the switchblade 1, a spring clip 24 with opposite hooked ends 25 and 25 seated inrecesses 26 and 26 in the ends of the contact fingers 8 biases theContact fingers open.

For adjusting the position of the ends 10 of the contact lingers 8transverse to the plane of relative movement of the contacts so as tocenter the blade 1 between the contact tips 10, a set screw 27 isprovided in the central supporting member 9 which engages the sleeve 19so that the latter may be adjusted up or down as shown in FIG. l andlocked in position by the set screw.

It will be observed that as the ends 10 of the contact fingers 8 arespread apart by the blade contact 1 that the pressure produced by thesprings 23 will cause firm engagement between the relatively sharp edgesof the vholes 15 and the hemispherical surfaces 13--13 of theprojections 11-11 thus assuring good electrical contact over a widerange of angular positions of the contact fingers 8.

While there has been shown and described a particular embodiment of theinvention, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention and,therefore, it is intended by the appended claims to cover all suchchanges and modifications as fall within the true spirit and scope ofthe invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an electrical switch of the type having a pair of relativelymovable selectively engageable and disengageable contacts, one of saidcontacts being a blade contact and the other being a double fingercontact whose fingers engage opposite sides of said blade contact assaid contacts are moved into and out of engagement and which contactfingers pinch said blade contact therebetween when said contacts are inengagement, said double finger contact having a central supportingmember for its double contact fingers, said central supporting memberhaving two pairs of projections extending from opposite sides thereofand spaced lengthwise of said contact fingers, the pair of projectionsfarthest from said blade contact being aligned in a direction transverseto said Contact fingers and having hemispherically shaped ends, circularholes through said contact fingers of a diameter slightly less than thediameter of said hemispherically shaped ends, said holes beingrespectively seated on said hemispherically shaped ends so as to form aball and socket type universally pivoted electromechanical connectionbetween said contact fingers and said central supporting member, theother pair of projections extending through a second pair of alignedholes in said contact fingers, and resilient means for biasing saidcontact fingers toward each other, said ball and socket type connectionbeing the principal electrical connection between said contact fingersand said central member.

2. In an electrical switch of the type having a pair of relativelymovable selectively engageable and dis-` engageable contacts, one ofsaid contacts being a blade contact and the other being a double fingercontact whose fingers engage opposite sides of said blade contact assaid contacts are moved into and out of engagement and which contactfingers pinch said blade contact therebetween when said contacts are inengagement, said double finger contact having a central supportingmember for its double contact fingers, said central supporting memberhaving two pairs of projections extending from opposite sides thereofand spaced lengthwise of said contact fingers, the pair of projectionsfarthest from said blade contact being aligned in a direction transverseto said contact fingers and having hemispherically shaped ends, circularholes through said contact fingers of a diameter slightly less than thediameter of said hemispherically shaped ends, said holes beingrespectively seated on said hemispherically shaped ends so as to form aball and socket type universally pivoted electromechanical connectionbetween said contact fingers and said central supporting member, theother pair of projections extending through a second pair of alignedholes in said contact fingers, resilient means associated with saidother pair of projections and said contact fingers for biasing thelatter toward each other, and connecting means between the ends of saidcontact fingers which are most remote from said blade contacts forrestraining the motion produced by said resilient biasing means, saidball and socket type connection being the principal electricalconnection between said contact ngers and said central member.

3. In an electrical switch of the type having a pair of relativelymovable selectively engageable and disengageable contacts, one of saidcontacts being a blade contact and the other being a double fingercontact whose fingers engage opposite sides of said blade contact assaid contacts are moved into and out of engagement and which contactfingers pinch said blade contact therebetween when said contacts are inengagement, said double finger contact having a central supportingmember for its double contact fingers, said central supporting memberhaving two pairs of projections extending from opposite sides thereofand spaced lengthwise of said contact fingers, the pair of projectionsfarthest from said blade Contact being aligned in a direction transverseto said contact fingers and having hemispherically shaped ends, circularholes through said contact fingers of a diameter slightly less than thedameter of said hemispherically shaped ends, said holes beingrespectively seated on said hemispherically shaped ends so as to form aball and socket type universally pivoted electromechanical connectionbetween said contact fingers and said central supporting member, theother pair of projections extending through a second pair of alignedholes in said contact fingers, resilient means associated with saidother pair of projections and said contact fingers for biasing thelatter toward each other, connecting means between the ends of saidcontact fingers which are most removed from said blade contacts forrestraining the motion produced by said resilient biasing means, andmeans for adjusting the position of said other pair of projectionstransverse to the plane of relative movement of said contacts foraligning said contacts relative to each other with respect to saidplane, said ball and socket type connection being the principalelectrical connection between said contact fingers and said centralmember.

4. In an electrical switch of the type having a pair of relativelymovable selectively engageable and disengageable contacts, one of saidcontacts being a blade contact and the other being a double fingercontact whose fingers engage opposite sides of said blade contact with aside- 4wise as opposed to an end-wise wiping action as said contacts aremoved into and out of engagement and which contact fingers pinch saidblade Contact therebetween when said contacts are in engagement, saiddouble finger contact having a central supporting member for its doublecontact fingers, said central supporting member having two pairs ofprojections extending from opposite sides thereof and spaced lengthwiseof said contact fingers, the pair of projections farthest from saidblade contact being aligned in a direction transverse to said contactfingers and having hemispherically shaped ends with a reduced diameteroutwardly extending projection thereon, circular holes through saidcontact fingers of a diameter slightly less than the diameter of saidhemispherically shaped ends, said contact fingers being respectivelyseated 'tion produced by said resilient biasing means, and means foradjusting the position of said other pair of projections transverse tothe plane of relative movement of said con tacts for aligning saidcontacts relative to each other with respect to said plane, said balland socket type connection being the principal electrical connectionbetween said contact fingers and said central member.

References Cited in the file of this patent FOREIGN PATENTS 851,729Great Britain Oct. 19, 1960

1. IN AN ELECTRICAL SWITCH OF THE TYPE HAVING A PAIR OF RELATIVELYMOVABLE SELECTIVELY ENGAGEABLE AND DISENGAGEABLE CONTACTS, ONE OF SAIDCONTACTS BEING A BLADE CONTACT AND THE OTHER BEING A DOUBLE FINGERCONTACT WHOSE FINGERS ENGAGE OPPOSITE SIDES OF SAID BLADE CONTACT ASSAID CONTACTS ARE MOVED INTO AND OUT OF ENGAGEMENT AND WHICH CONTACTFINGERS PINCH SAID BLADE CONTACT THEREBETWEEN WHEN SAID CONTACTS ARE INENGAGEMENT, SAID DOUBLE FINGER CONTACT HAVING A CENTRAL SUPPORTINGMEMBER FOR ITS DOUBLE CONTACT FINGERS, SAID CENTRAL SUPPORTING MEMBERHAVING TWO PAIRS OF PROJECTIONS EXTENDING FROM OPPOSITE SIDES THEREOFAND SPACED LENGTHWISE OF SAID CONTACT FINGERS, THE PAIR OF PROJECTIONSFARTHEST FROM SAID BLADE CONTACT BEING ALIGNED IN A DIRECTION TRANSVERSETO SAID CONTACT FINGERS AND HAVING HEMISPHERICALLY SHAPED ENDS, CIRCULARHOLES THROUGH SAID CONTACT FINGERS OF A DIAMETER SLIGHTLY LESS THAN THEDIAMETER OF SAID HEMISPHERICALLY SHAPED ENDS, SAID HOLES BEINGRESPECTIVELY SEATED ON SAID HEMISPHERICALLY SHAPED ENDS SO AS TO FORM ABALL AND SOCKET TYPE UNIVERSALLY PIVOTED ELECTROMECHANICAL CONNECTIONBETWEEN SAID CONTACT FINGERS AND SAID CENTRAL SUPPORTING MEMBER, THEOTHER PAIR OF PROJECTIONS EXTENDING THROUGH A SECOND PAIR OF ALIGNEDHOLES IN SAID CONTACT FINGERS, AND RESILIENT MEANS FOR BIASING SAIDCONTACT FINGERS TOWARD EACH OTHER, SAID BALL AND SOCKET TYPE CONNECTIONBEING THE PRINCIPAL ELECTRICAL CONNECTION BETWEEN SAID CONTACT FINGERSAND SAID CENTRAL MEMBER.